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WEIGHING APPARATUS Filed Nov. 9. 1966 15 Sheets-Sheet 1s aJ/M United States Patent 3,390,733 WEIGHHIG AEPARATUS Tadashi Takahashi, 169 Yokoya, Uosaki-cho,

Higashinada-ku, Kobe, Japan Continuation-impart of application Ser. No. 428,081, Jan. 26, 1965. This application Nov. 9, 1966, Ser. No. 593,121 Claims priority, application Japan, Feb. 4, 1964, 39/ 5,372 5 Claims. (Cl. 177-169) ABSTRACT OF THE DISCLOSURE A weighing and dispensing apparatus having a pivotally supported balance beam equipped with a scale plate pivotally connected thereto and a counter balance means connected thereto. The apparatus includes support means limiting gravitational movement of the scale plate to a fixed limiting position, and includes a reversible motor operable, responsive to engagement of the scale plate with the support means, to rotate its output shaft which is connected by a transmission means to the balance beam so as to displace the balance beam in a direction to increase the force of the counter balance means in proportion to the angular displacement of the motor output shaft.

The scale plate is disengaged from the support means when the counter balance force balances the gravitational force acting on the scale plate. Means are provided to measure the difference between the angular displacement of the shaft, when the counter balance force balances the gravitational force, and a predetermined angular displacement of the shaft, when the balance beam is balanced with a preselected weight.

Background of the invention This application is a continuation-in-part of my abandoned application Ser. No. 428,081, filed Jan. 26, 1965, for Weighing Method.

This invention relates to a weighing apparatus, more particularly to a weighing apparatus for dispensing pourable commodities into a plurality of sub-groups of a certain predetermined constant weight, wherein said commodities can be either in solid state, such as masses, grains, and powder particles, or in liquid state, and to a weighing apparatus for assorting a plurality of articles according to the weight thereof.

There are various continuous weighing machines which have hitherto been used for dispensing and assorting operations, but these machines generally have shown considerable errors.-These errors are due mainly to the fact that the pourable commodities or articles to be weighed are dropped onto a scale plate of the machine and the mechanical impulse force caused by such dropping acts upon a balancing system of the machine so as to increase the apparent net weight of the commodities or articles to be weighed. Thus, the apparent weight of the commodities or articles determined by such machines tends to exceed the true weight thereof, or the quantity thereof tends to be short of the true quantity for the weight thus determined. To avoid such errors, it has been the practice to shift the balanced position of the machine toward the plus side. However, such shifting of balancing position enables only empirical compensation of deficit weight or weight deficiency, and itdoes not enable true and accurate weighing for dispensation. In addition, the flow of the pourable commodities or articles to be weighed shows considerably irregularity, especially when such commodities or articles to be weighed are of massive or granular shape, the flow rate 3,390,733 Patented July 2, 1968 of said massive or granular-shaped commodities or articles falling from the chute onto the weighing machine is ever changing, and hence the magnitude of the impulse force acting on the weighing machine in addition to the gravitational force representing the true weight of the commodities or articles is not constant, which leads to an inevitable error due to the unpredictable impulse forces.

The present invention provides a weighing operation which is not affected by such impulse forces due to falling of the commodities or articles delivered to a weighing machine. The weighing operation of the invention is effected by initially absorbing the impulse forces, of commodities or articles dropped onto the scale plate of a weighing device, by a rigid support member, in order to prevent these forces from being transmitted to the balancing system. Thereafter, a portion of the balancing system is shifted, by applying to the balancing system, an external force in a direction to relieve the rigid support member from the weight of the commodities or articles, and detecting or measuring the displacement of the balancing system required to shift the same from the initial no-load balanced condition to the loaded balanced condition with the commodities or articles placed on the Weighing machine.

The principal object of the invention is to provide a weighing apparatus for dispensing pourable commodities into a number of groups of a desired weight, in which a pre-dispensed quantity of said commodities is placed on a scale plate pivotally connected to a balance beam, the pre-dispensed quantity weighing less than the desired weight, the gravitational force acting on the commodities on the scale place is supported by a support means to hold the scale supported at a fulcrum thereof and connected to a counterbalance means so as to have a variable counterbalance force acting at a point of the balance beam, a reversible motor is started responsive to the supporting of said scale plate by the support means, an external force is applied to a point of the balance beam so as to increase the variable counterbalance force by transmitting the rotation of the shaft of the reversible motor through a transmission means, the external force being proportional to the magnitude of the angular displacement of the shaft, the supporting of the scale plate is released when the variable counterbalance force is so increased as to substantially balance the gravitational force acting on the commodities on the scale plate, the weight of commodities on the scale plate is represented by the angular displacement of the shaft when the scale plate is released from the support, a deficit weight of the predispensed commodities from the desired weight is detected as the difference between the angular displacement of the shaft when the variable counterbalance force balances the pre-dispensed commodities on the scale plate and a predetermined angular displacement of the shaft when the balance beam is balanced with commodities of desired weight on the scale plate, and the pro-dispensed quantity of commodities is supplemented by feeding the commodities, in an amount equal to the deficit weight, by a supplementing means actuated by a relay means responsive to detection of the deficit weight.

Another object of the invention is to provide a weighing apparatus for sorting articles according to weight thereof, in which an article is placed on a scale plate pivotally connected to a balance beam, the gravitational force acting on the article on the scale plate is supported by a support means to hold the scale plate at a certain position, the balance beam being pivotally supported at a fulcrum thereof and connected to a counterbalance means so as to have a variable counterbalance force acting at a point of the balance beam, a reversible motor is started responsive to supporting of the scale plate by the support means, an external force is applied to a point of the balance beam so as to increase the variable counterbalance force by transmitting the rotation of the shaft of the reversible motor through a transmission means, the external force being proportional to the magnitude of the angular displacement of the shaft, and the scale plate is inverted so as to transfer the article to a sorting means when the variable counterbalance force is so increased as to substantially balance the gravitational force acting on the article on the scale plate, the sorting means having a shaft adapted to be rotated through an angle proportional to the angular displacement of the motor shaft.

It is another object of the invention to provide a weighing apparatus for dispensing pourable commodities into a number of groups of a desired weight, in which a predispensed quantity of the commodities is placed on a scale plate pivotally connected to a balance beam, the pre-dispensed quantity weighing less than the desired weight, the gravitational force acting on the commodities on the scale plate is supported by a support means to hold the scale plate at a certain position, the balance beam being pivotally supported at a fulcrum thereof and connected to a counterbalance means so as to have a variable counterbalance force acting at a point of the balance beam, a reversible motor is started responsive to supporting of the scale plate by the support means, an external force is supplied to a point of the balance beam so as to increase the variable counterbalance force by transmitting the rotation of the shaft of the reversible motor through a transmission means, the external force being proportional to the magnitude of the angular displacement of the shaft of said reversible motor, the supporting of the scale plate is released when the variable counterbalance force is so increased as to substantially balance the gravitational force acting on the commodities on the scale plate, the shaft is connected to a transmission means to actuate a movable member of a differential transformer responsive to release of the supporting of the scale plate, the weight on the commodities of the scale plate is represented by the angular displacement of the shaft when the scale plate is released from said support, a cam having at least one notch formed on the circumference thereof is secured to the shaft of the reversible motor, an actuating bar of magnetic material is provided to fit in the notch of the cam, the actuating bar being located at a position related with that angular position of the shaft at which the variable counterbalance force is increased to a level balancing the desired weight, the actuating bar is biased with a spring force to keep the actuating bar normally away from the cam, a solenoid is provided to force the actuating bar into the notch of the cam against the spring force, the solenoid is energized responsive to release of the scale plate from the support means to force the actuating bar into the notch of the cam to rotate the shaft of the reversible motor to such angular position, the difference between the weight of the pre-dispensed commodities and the desired weight is detected, by means of the differential transformer, as the difference between the angular displace ment of the shaft when the variable counterbalance force balances the pre-dispensed commodities on the scale plate and a predetermined angular displacement corresponding to such angular position of said shaft, and the quantity of pre-dispensed commodities is supplemented by feeding commodities of a weight equal to the deficit weight by a supplementing means actuated by a relay means responsive to detection of the deficit weight.

In the following description, what is meant by the loaded balanced position is the balanced position of the balance beam with the commodities or articles loaded on the weighing device, What is meant by the standard weight is the desired weight of the commodities preselected from a particular weighing operation of the weighing device, such as the weight assigned to each capsule of medicine to be dispensed when the commodities to be weighed are medicine, and what is meant by the equalizing deflection is the deflection of a certain point of the balance beam between its no-load balanced position and its loaded-balanced position when the standard weight of commodities is loaded on the weighing device.

Additionally, the term deficit weight, as used hereinafter, refers to the weight deficiency necessary to be supplied to bring the weight of the commodities or articles up to the standard weight.

For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a diagrammatic illustration of a weighing device usable in performing the method of the invention;

FIG. 2 is a wiring diagram of the device of FIG. 1;

FIGS 3 to 5 illustrate other embodiments of weighing devices usable in performing the method of the invention;

FIG. 6 is a diagrammatic illustration of an assorting device embodying the method of the invention;

FIG. 7 is a perspective view illustrating another type of assorting device embodying the method of the invention;

FIGS. 8 to 10 are diagrammatic views illustrating other embodiments of weighing devices;

FIGS. 11-A, B, and C, and FIGS. 12-A, B, and C, illustrate examples of deviation detecting means;

FIG. 13 is a partial wiring diagram of the means shown in FIGS. ll-A to 12C, illustrating control means for adding the pourable commodities to each group to bring it to the desired standard weight;

FIG. 14 is a diagrammatic illustration of another weighing device usable in performing the method of the invention;

FIG. 15 is a wiring diagram of the device of FIG. 14;

FIGS. 16A and B are a diagrammatic illustration and a partial wiring diagram, respectively, illustrating a dispe'nsing device usable in performing the method of the invention;

FIGS. l7-A and B are a perspective view and a vertical sectional view, respectively, of a supplementing device for use with a weighing device;

FIGS. 18 and 19 illustrate further embodiments of weighing devices; and

FIG. 20 is a wiring diagram of the devices shown in FIGS. 18 and 19.

At first, the procedure of dispensing pourable commodities into a number of groups of a standard weight, such as filling each of a plurality of separate bags or capsules with a quantum of desired commodities of a preselected weight, will be described.

Referring to FIG. 1, a balance beam 1 is supported at a fulcrum 2 located at the top end of a vertical bar 20 which is movable along fixed guide members 2a and 2b, and a Roberval lever lb is connected to balance beam 1 through vertical bars 10 and 2. Vertical bar 10 is positioned at one end of balance beam 1 and provided with a scale plate 7 to receive the commodities to be weighed and with a lug 1a to actuate a movable contact a of a limit switch LS. A counterbalance spring 8 is connected to the opposite end of balance beam 1, with the lower end of spring 8 being connected to a fixed point 11 and the upper end to balance beam 1 by means of an adjusting screw 12 so as to keep scale plate 7 in a balanced position under no load. Support members 9 and 10 are provided to receive and support the impulsive force caused either by placing commodities to be weighed onto scale plate 7 or by removing the same from scale plate 7.

Scale plate 7 is spaced from support member 9 by a certain predetermined distance in the no load condition. Upon placing commodities to be weighed onto scale plate 7, the distance between scale plate 7 and support member 9 is decreased and the electric circuit between contacts a and b of limit switch LS is closed by engagement of lug 1a with the movable blade of contact a. Furthermore, upon removing commodities from plate 7, the above distance between plate 7 and support member 9 is increased beyond the value at no load, and the electric circuit between contacts a and c is closed by engagement of lug 1a with the movable blade of contact a.

A shaft 4 driven by a reversible motor 3 is engaged with vertical bar 2c through the medium of a pinion 5, secured to shaft 4, and a rack 6, secured to vertical bar 2c, in order to shift vertically fulcrum 2 and, accordingly balance beam 1. The magnitude of the vertical displacement of fulcrum 2 of beam 1 can be easily detected by measuring the angular displacement of shaft 4. The displacement of fulcrum 2 represents the displacement of the counterbalance spring 8 as described hereinafter. A dial plate 13, having a series of graduations, is secured to shaft 4 to rotate therewith, and the angular displacement of plate 13 and shaft 4 can be read easily by means of a fixed pointer 14.

In order to detect electrically the angular displacement of shaft 4, the latter is connected to a deviation detector 16 in such a manner that a contact point d, provided at the free end of a rotary arm 15 secured to shaft 4, makes a direct contact with the proper one of a series of contacts e, which are disposed substantially along a circle on a sup port framework 16a, responsive to the magnitude of the angular displacement of shaft 4. It is permissible to use framework 16a holding the contacts e as a bearing holder for the shaft 4.

FIG. 2 illustrates the electric circuit of the device of FIG. 1, wherein 17 is an electric power source, 18 a capacitor connected between a terminal b of a winding W and a terminal c of another winding W of the reversible motor 3, 13a and 19b relays, 20 an indicator of deviation detector 16, and 21 a DO power source.

The weighing operation of the device of FIG. 1 will now be described. The pourable commodities are predispensed into a number of groups, having a volume roughly equivalent to the desired weight, by means of a suitable measure. Upon placing one of such pre-dispensed groups on scale plate 7, balance beam 1 rotates around its fulcrum 2 in a counterclockwise direction, as viewed from the front of FIG. 1, and the circuit between the contact a and b is closed by means of the downward movement of lug 1a. Then scale plate 7 and balance beam 1 are held stationary by supporting the gravitational force, acting on the commodities, by support member 9. With contacts a and b closed, an operating circuit of reversible motor 3 is completed, which traces from the terminal a of power source 17 through the lead wire A, contacts a, b, terminal b, winding W terminal 1" and lead wire D and back to the terminal j of power source 17. Accordingly, the reversble motor is rotated in a clockwise direction to lift fulcrum 2 of balance beam 1 through a transmission mechanism comprising pinion 5 and rack 6. Since scale 7 is held stationary at support member 9, as fulcrum 2 is lifted gradually responsive to the rotation of reversible motor 3, counterbalance spring 8 is elongated to cause an increase in the magnitude of the elastic force acting at the righthand end of balance beam 1 so as to eifect a clockwise rotation of balance beam 1 around fulcrum 2 (as viewed from the front of FIG. 1). If the above elastic force acting at the righthand end of the balance beam is increased sufliciently to balance the gravitational force acting at the lefthand end thereof, the scale plate is going to move upward leaving the support member 9. Thus, as fulcrum 2 is further lifted, lug 1a is also raised to interrupt the circuit between contacts a and b to stop the clockwise rotation of reversible motor 3. (For the sake of simplicity, such a position of the balance beam as to cause disengagement of scale plate 7 from support member 9 and interruption of the circuit between contacts a and b will be referred to as the balanced position of the balance beam hereinafter.)

At the same time, the magnitude of the angular displacement of shaft 4, which is directly proportional to the vertical elongation of counterbalance spring 8, can be read as the number of graduations on dial plate 13 passing indicating needle 14. It is now apparent that the above number of graduations is proportional to the weight of the commodities to be weighed.

Furthermore, as shaft 4 stops rotating, contact point d at the tip end of rotary arm 15 is also stopped, while keeping direct contact with a proper one of the deviation indicating contacts e. Thereby, the energizing circuit of indicator 20 of the deviation detector is completed, which traces from a common terminal at one side of indicator 20 through the lead wire H, the DC. power source 21, the lead wire G, contacts of the relays 19a and 19b (to be closed under these conditions), contact at of rotary arm 15, and the properly selected one of the deviation indicating contact points 2, back to the said common terminal of the indicator 20. Thus, a proper element of indicator 20, such as a selected one of a series of indicating lamps, is energized responsive to de-energization of relays 19a or 19b previously referred to following the interruption of the circuit between contacts a and b of limit switch LS. In other words, if the indicating lamp representing a zerodeviation is energized, it means that the weight of the object on scale plate 7 is equal to the desired value (for the sake of simplicity, such a position of the deviation detector as to energize the indicating element representing a zerodeviation will be referred to hereinafter as the equalized position of the deviation detector), while, when any other indicating element, such as a lamp, of the indicator is energized, it means that the weight of the commodities on scale plate 7 is either in excess of or short of the desired standard weight by the degree represented by the indicating element, as will be described in further detail hereinafter.

Upon removal of the commodities to be weighed, the balance of forces acting on both ends of balance beam 1 is lost, and balance beam 1 is rotated clockwise around its fulcrum 2 by the elastic force of the elongated counterbalance spring 8 to close the circuit between contacts a and c by the upward movement of the lug 1a. Thereby, the circuit of reversible motor 3 effective to rotate it in a counterclockwise direction is energized, which circuit traces from terminal a of power source 17 through lead wire A, contacts a, c, lead wire B (a switch 60 is not used in this embodiment), terminal (2 winding W terminal 1'" of reversible motor 3, and the lead wire E, and back to the terminal j of power source 17. Thereby, the reversible motor is rotated in a counterclockwise direction to lower fulcrum 2 of the balance beam 1. Since the righthand end of balance beam 1 is held stationary at support member 10 by the elastic force of counterbalance spring 8 under these conditions, as fulcrum 2 is lowered, the lefthand end of balance beam 1 and, accordingly, scale plate 7, are also lowered until the distance between scale plate 7 and support member 9 is reduced to the aforementioned initial balanced distance and the electric circuit between contacts a and c is interrupted. Thus, the initial balanced position of balance beam 1 is restored.

It should be noted here that the limit switch LS having contacts a, b and c, in the above embodiment, can be replaced by any other suitable type of device, such as a switching device including a photoelectric cell. In the case of a photoelectric cell switch, mechanical inertia inherent to the limit switch contacts, such as a, b and c, can be eliminated and the accuracy in the weighting operation can be increased accordingly.

In FIG. 2, d and e' designate terminals on the devia tion detector connected to the rotary arm contact a and deviation detecting contacts e respectively.

FIG. 3 illustrates another weighing device which is characterized in that a counterweight 8' is used in conjunction with a conuterbalance spring 8 at the same end of a balance beam 1, and that a cam 5' and a cam follower bracket 6' cooperating with cam 5 are used instead of the combination of pinion Sand rack 6 of the device of FIG. 1, in order to allow unidirectional continuous rotation of motor 3 and vertical reciprocation of fulcrum 2 responsive to such unidirectional rotation. Furthermore, in the weighing device of FIG. 3, the deviation indicating circuit is energized by a device consisting of a switch, induction coils, and a clutch means, without interrupting the rotation of the motor 3. FIG. 3-A shows the electrical control circuit of the weighing device illustrated in FIG. 3.

In the device as shown in FIG. 3, weight member 8, which is substantially lighter than the desired weight of commodities, is placed on a plate connected to the righthand end of balance beam 1, as viewed from the front of FIG. 3, prior to placing the commodities to be weighed onto scale plate 7. Then the righthand end of balance beam 1 is lowered, and held stationary by support member 10. Accordingly, as cam 5 secured to shaft 4 is rotated unidirectionally by means of driving motor 3, vertical rod 20 and hence fulcrum 2 of balance beam 1 are vertically reciprocated in accordance with the configuration of cam 5. Thereby, the vertical rod at the lefthand end of the balance beam, and hence scale plate 7, are also vertically reciprocated, causing the circuit between contacts a and b of limit switch S to be closed and opened, when scale plate 7 reaches certain positions relative to support member 9, by means of the engagement between switch S and lug 1a extending from vertical rod 10. At the same time, a proper deviation indicating contact for the no-load condition, say a is selected out of the series of deviation indicating contacts e by means of a deviation detector to be described later. Upon closing the circuit, between contacts a and b, a current is fed from the DC. power source 22 through a primary coil 23 of an induction device and a voltage is induced across the terminals of a secondary coil 24 of the induction device. The voltage thus induced across the secondary coil 24 is amplified by an amplifier 25 to energize an electromagnet 26 of a clutch means K. With electromagnet 26 being energized, deviation indicator 20 gives an indication of the deviation of the weight of the commodities on scale plate 7 from the desired weight, namely a deviation equal to the entire desired weight under the above no-load condition.

If commodities substantially heavier than counterweight 8 are placed on scale plate 7 when the latter is at the lowest position of its vertical reciprocation stroke, then the gravitational force acting on the commodities to be weighed is received by support member 9 to hold stationary both scale plate 7 and vertical rod 10. Accordingly, as shaft 4 and hence cam 5 are rotated, fulcrum 2 is raised and the righthand end of balance beam 1 is also forced to move upward, while causing elongation of counterbalance spring 8, until the composite force acting at the righthand end of beam 1, which is the sum of gravitational force acting on counterweight 8 and the elastic force of counterbalance spring 8 due to its elongation, is increased sufliciently to balance the gravitational force acting on the commodities on scale plate 7, with respect to fulcrum 2 of the balance beam 1. Thus, the balanced position of balance beam 1 is obtained.

After such a balanced position of beam 1 is attained, both ends of balance beam 1 are raised in parallel, in accordance with the rotation of shaft 4 and cam 5, in order to close the circuit between contacts a and b of limit switch S. With the contacts of limit switch S closed, deviation indicator 20 is energzed to indicate the selected one, say e of the series of deviation indicating contacts e as will be described hereinafter. Since the angular difference of the deviation indicating contact a from a preselected reference contact e can be easily made proportional to magnitude of the angular displacement of shaft 4, and, accordingly, to the elongation of counterbalance spring 8, the weight of the commodities on scale plate 7 may be detected by means of such angular difference. For instance, if the weight of the commodities on scale plate 7 at a certain moment coincides with the desired weight, then deviation indicator 20 will give a zero-deviation indication responsive to the selection of the proper deviation indicating contact s On the other hand, if the weight of the commodities placed on scale plate 7 is different from the desired weight by a certain amount, then another contact e is selected so as to indicate the weight difference properly.

Details of the clutch means actuated by electromagnet 26 and of the deviation detector or the selector of deviation indicating contacts will be described hereinafter. It should be noted here that the induction means are so adapted as to energize electromagnet 26 responsive only to closing operation of contacts a and b of limit switch S, and to de-energize electromagnet 26 upon completion of the closing operation. Thus the upward movement of fulcrum 2 after contacts a and b of limit switch S are closed does not afiect the indication of the deviation.

It is preferable to maintain the indication of the deviation for a suitable period of time by means of a suitable time delay means. In FIG. 3, 27 is a shifter having an armature cooperating with electromagnet 26, 28 a shaft pivotally supporting shifter 27, 29 a collecting roller, and 30 a collecting ring directly connected to the contact d. The weighing device of the type shown in FIG. 3 is suitable to carry out smooth and efficient automatic weighing and dispensing operation, particularly such operations in a continuous conveyor system. Unless a load is placed on scale plate 7, the device idles.

FIG. 4 illustrates another weighing device according to the invention, wherein the principles of the present invention are applied to a spring balance of conventional type. A conventional balance is enclosed in a fixed outer casing 31 which has a support member 9 for receiving scale plate 7, and there are a dial plate 14, an indicating needle 13, a balance beam 1 and a Roberval lever 1b placed in an inner casing 31a, which is in turn held in the fixed outer casing 31 in a vertically slidable manner by means of rollers 32.

In the device shown in FIG. 4, cam 5 mounted on shaft 4 driven by reversible motor 3 (not shown) causes vertical reciprocation of inner casing 31a together with vertical rod 2c, fulcrum 2 of the balance beam 1, dial plate 14 and retainer 11 of the counterbalance spring 8, at a certain predetremined rate, say at a uniform speed of V Then, when commodities are placed on the scale plate, the lower end of counterbalance spring 8, which is fixed to Roberval lever 1b, at a point intermediate to the fulcrum and the extreme lefthand end thereof as viewed from the front of FIG. 4, is moved at a speed slower than the speed of the inner casing 31a. Thereby, the counter balance spring 8 is gradually elongated as inner casing 31a is raised, while causing an increase in the magnitude of the elastic force acting on Roberval lever 1b in a vertically upward direction, until such upward elastic force is balanced with the gravitational force acting on the commodities to be weighed on scale plate 7. Furthermore, it can be seen easily that vertical rod 2d, connected to the extreme righthand end of balance beam 1 as viewed from the front of FIG. 4, is moved at a speed faster than the speed of easing 31a. Thereby, pointer 13 is rotated by means of the engagement between a pinion, secured to the rotary shaft of pointer 13, and a rack secured to vertical rod 2d.

Thus, with a limit switch LS and the reversible motor 3 similar to those described in detail with regard to FIG. 1, balance beam 1 is brought into a balanced position indicative of the weight of the commodities placed on scale plate 7, and the weight thereof can be shown on dial plate 14 as in the case of conventional spring balance. It is also permissible to use a two contact limit switch S as shown in FIG. 3, instead of the three contact limit switch LS, in the embodiment of FIG. 4.

A deviation indicating device in the weighing device of FIG. 4 consists of an indicating needle 33, secured to shaft 4, and a dial plate 34, instead of the combination of a rotary arm and a series of deviation indicating contacts e in the weighing devices of FIGS. 1 and 3.

FIG. 5 illustrates another weighing device in which a balance beam 1 is supported by a fixed fulcrum 2, instead of a movable fulcrum as shown in the aforementioned weighing devices, and both a counter weight 8' and a counterbalance spring 8 are placed on one end portion of the balance beam 1 with respect to fulcrum 2 thereof, say the righthand end portion thereof as shown in the figure. In the device of FIG. 5, an external force is applied to the same end of the balance beam connected to the counter balance spring, by means of a cam 5' acting through such spring.

Furthermore, in this device, the ratio of the linear displacement of counterbalance spring '8 to the angular displacement of cam 5 is made variable. If the commodities to be weighed comprise granular or powder particles of uniform size, it is convenient to express the deviation of the weight by multiples of a unit weight representing the weight of one such uniform size particle or multiple thereof, instead of deviation in absolute Weight, such as so many grams. The weighing device of FIG. 5 is provided not only with means for giving such indication of the deviation of weight in terms of multiples of a certain predetermined unit, but also with means for adjusting the magnitude of such predetermined unit weight in accordance with the kind of the commodities to be weighed.

In order to facilitate the modification of the magnitude of such unit weight, a vertical rod 38 is fixed at the free end of the counterbalance spring 8 and guided by a vertical guide 39 so as to allow vertical movement thereof, and a rollar 40, fitted in a grooved portion 41 of a horizontal lever 42, is rotatably mounted on a certain point of vertical rod 38 to link together vertical rod 38 and horizontal lever 42. Horizontal lever 42 is hinged to a threaded rod 45 for pivoting around a pintle 44 of a hinge 43, and the threaded rod 45 in turn mounted on a fixed bracket, by means of nuts mating with the thread on the rod, in such a manner that rod 45 and accordingly pintle 44 may be shifted in a horizontal direction by turning the nuts. Thus, the ratio between the distance from .the contact point of lever 42 with cam 5' to roller 40,

and the distance from roller 40 to pintle 44, can be adjusted by moving threaded rod 45 horizontally by turning the nuts fastening rod 45 to the fixed bracket. Thus, the magnitude of the elongation of counterbalance spring 8 per unit angular displacement of cam 5' can be adjusted at will within a certain range, so as to bring about the modification of aforementioned unit weight per one graduation of a dial plate 34".

It is apparent now to those skilled in the art that the weight of the commodities to be weighed, or the deviation of the same from the desired weight, can be detected by the magnitude of the angular displacement of shaft 4 and indicated on dial plate 34" by an indicating pointer 33" in a manner similar to any of the methods described with reference to FIGS. 1 to 4.

In order to calibrate the graduations of the dial plate and thread rod 45, commodities of desired standard weight are first placed on scale plate 7 and, when contacts a and b are opened as the balanced position of the balance beam is obtained by means of the rotation of shaft 4 driven by the reversible motor, pointer 33" is set at the zero-deviation point of dial plate 34". Then a certain amount of commodities, having a weight corresponding to multiples of the predetermined unit weight, is added to or removed from scale plate 7, and the position of threaded rod 45 is adjusted by turning the nuts, which fasten the rod to the fixed bracket, back and forth so that pointer needle 33" indicates the graduation corresponding to such multiple of the predetermined unit weight.

It is preferable to provide a series of suitable graduations on rod 45 to give an indication of the ratio between the angular rotation of cam 5 and the corresponding linear displacement of counterbalance spring 8, or of the value of the unit weight per graduation on the dial plate.

In order to ensure the return of cam 5 after the removal of the commodities to be weighed from scale plate 7, in the device of FIG. 5, another limit switch 60, consisting of contacts 0" and c which are inserted in series into the circuit of the reverse winding W of reversible motor 3 as shown in FIG. 2, is provided. In other words, in the device of FIG. 5, the rotation of motor 3 in the reverse direc ion, following the removal of the commodities from scale plate 7, is interrupted by the action of limit switch 60 even when contacts a and c are still kept closed, and the weighing device becomes ready for the next weighing operation.

The application of the present invention to assortment of a plurality of individual articles by weight, such as assortment of applies by weight there-of into a number of groups, will now be described.

FIG. 6 shows an example of devices for assorting articles by weight according to the invention, in which a counterbalance spring 8 is connected to the same end of balance beam 1 as that which receives the gravitational force acting on the article to be Weighed. The article to be weighed and assorted is placed on scale plate 7 connected to one end of balance beam 1 through vertical rod 10, while placing a counterweight 8, which is slightly lighter than the lightest one of the articles to be weighed, on another scale plate, connected to the opposite end of balance beam 1 with respect to fulcrum 2 through another vertical rod 1d, so that the gravitational force acting on the article to be weighed is received by fixed support member 9. Scale plate 7 is hinged at the end of vertical rod 10 so as to be turned over in a counterclockwise direction away from a stopper 1s.

The downward movement of vertical rod 10, following the placement of the article to be weighted onto scale plate 7, closes the circuit between contacts a and b to cause rotation of reversible motor 3 in a clockwise direction, as described in connection with FIG. 1. Thereby, a vertical rod 42b hinged to a horizontal lever 42, which is supported by a movable fulcum to transmit the vertical movement of rod 42b to counterbalance spring 8, is moved downward, causing rotation of lever 42 around fulcrum 80 in order to elongate counterbalance spring 8 until the composite force, of the gravitational force acting on the article to be weighed and the elastic force due to elongation of spring 8, is balanced with the gravitational force acting on counterweight 8. Then balance beam 1 is brought into its balanced position. Upon attainment of the balanced position of balance beam 1, the circuit between contacts a and b is opened to stop rotation of shaft 4 and, accordingly, elongation of counterbalance spring 8 through vertical rod 42b and horizontal lever 42.

The annular displacement of shaft 4, from the initial no-l-oad balance-d position to the balanced position with the article placed on scale plate 7, is proportional to the weight of the article provided that the Weight of counter- Weight '8' is constant. Accordingly, if a vertical shaft 70 of the assorting device is rotated responsive to the rotation of shaft 4, by means of gearing means 71, the outlet of a flexible chute 74 is brought to a selected one of a series of classified sections 73a, 73b, 73c of an assor-ting chamber 73. This is effected by means of the rotation of a guide arm 72 secured to vertical shaft 70, as shown in FIG. 6. Thus, the article weighed by the weighing device is simultaneously assorted and, on tilting scale plate 7, is delivered into the selected section of receiving chamber 76 in accordance with the magnitude of the angular displacement of shaft 4. In FIG. 6, 70a and 70b are bearings of vertical shaft 70. I

The operation of turning over or tilting scale plate 7 to forward the weighed article to flexible chute 74 can be, for instance, achieved by means of a lever 75 actuated 

